Endoscope having a guide tube

ABSTRACT

An endoscope having a guide tube is described herein. The assembly has an endoscope which is slidably insertable within the lumen of a guide tube. The guide tube is configured to be rigidizable along its entire length from a relaxed configuration. The endoscope has a steerable distal portion to facilitate the steering of the device through tortuous paths. In the relaxed configuration, a portion of the guide tube is able to assume the shape or curve defined by the controllable distal portion of the endoscope. Having assumed the shape or curve of the endoscope, the guide tube may be rigidized by the physician or surgeon to maintain that shape or curve while the endoscope is advanced distally through the tortuous path without having to place any undue pressure against the tissue walls.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of U.S. patent application Ser. No.10/139,289 filed May 2, 2002, which is a continuation-in-part of U.S.patent application Ser. No. 09/969,927 filed Oct. 2, 2001, which is acontinuation-in-part of U.S. patent application Ser. No. 09/790,204filed Feb. 20, 2001, which claims priority of U.S. Provisional PatentApplication Serial No. 60/194,140 filed Apr. 3, 2000, each of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates generally to endoscopes andendoscopic medical procedures. More particularly, it relates to a methodand apparatus to facilitate insertion of a flexible endoscope along atortuous path using a guide tube apparatus, such as for colonoscopicexamination and treatment.

BACKGROUND OF THE INVENTION

[0003] An endoscope is a medical instrument for visualizing the interiorof a patient's body. Endoscopes can be used for a variety of differentdiagnostic and interventional procedures, including colonoscopy,bronchoscopy, thoracoscopy, laparoscopy and video endoscopy.

[0004] Colonoscopy is a medical procedure in which a flexible endoscope,or colonoscope, is inserted into a patient's colon for diagnosticexamination and/or surgical treatment of the colon. A standardcolonoscope is typically 135-185 cm in length and 12-19 mm in diameter,and includes a fiberoptic imaging bundle or a miniature camera locatedat the instrument's tip, illumination fibers, one or two instrumentchannels that may also be used for insufflation or irrigation, air andwater channels, and vacuum channels.

[0005] The colonoscope is inserted via the patient's anus and isadvanced through the colon, allowing direct visual examination of thecolon, the ileocecal valve and portions of the terminal ileum. Insertionof the colonoscope is complicated by the fact that the colon representsa tortuous and convoluted path. Considerable manipulation of thecolonoscope is often necessary to advance the colonoscope through thecolon, making the procedure more difficult and time consuming and addingto the potential for complications, such as intestinal perforation.

[0006] Steerable colonoscopes have been devised to facilitate selectionof the correct path though the curves of the colon. However, as thecolonoscope is inserted farther and farther into the colon, it becomesmore difficult to advance the colonoscope along the selected path. Ateach turn, the wall of the colon must maintain the curve in thecolonoscope. The colonoscope rubs against the mucosal surface of thecolon along the outside of each turn. Friction and slack in thecolonoscope build up at each turn, making it more and more difficult toadvance and withdraw the colonoscope. In addition, the force against thewall of the colon increases with the buildup of friction. In cases ofextreme tortuosity, it may become impossible to advance the colonoscopeall of the way through the colon.

[0007] Steerable endoscopes, catheters and insertion devices for medicalexamination or treatment of internal body structures are described inthe following U.S. patents, the disclosures of which are herebyincorporated by reference in their entirety: U.S. Pat. No. 4,543,090;4,753,223; 5,337,732; 5,337,733; 5,383,852; 5,487,757 and 5,662,587.

BRIEF SUMMARY OF THE INVENTION

[0008] An endoscopic assembly and method of advancing the assembly whichis able to traverse tortuous paths, such as the colon, withoutexcessively contacting the walls of the colon is described herein. Theassembly generally comprises a combination of an endoscope which isslidably insertable within the lumen of a guide tube. The endoscope maybe any conventional endoscope having a shaft which extends from ahandle. The distal end of the shaft preferably comprises a controllabledistal portion which may be manipulated to facilitate the steering ofthe assembly through the tortuous path. The guide tube may be aconventional flexible conduit which is configured to be rigidizablealong its entire length from a relaxed configuration. In the relaxedconfiguration, a portion of the guide tube is able to assume the shapeor curve defined by the controllable distal portion of the endoscope.Having assumed the shape or curve of the endoscope, the guide tube maybe rigidized by the physician or surgeon to maintain that shape orcurve.

[0009] Alternatively, the guide tube may also be used with an endoscopehaving an automatically controlled proximal portion and a selectivelysteerable distal portion. Such a controllable endoscope may have adistal portion which is manually steerable by the physician or surgeonto assume a shape to traverse an arbitrary curved path and a proximalportion which is automatically controlled by, e.g., a computer, totransmit the assumed shape along the proximal portion as the endoscopeis advanced or withdrawn. More detailed examples are described incopending U.S. patent application Ser. No. 09/969,927, which has beenincorporated above by reference in its entirety.

[0010] The guide tube may be comprised of a plurality of individualsegments which are linked adjacent to one another via one or moretensioning wires or elements. These tensioning elements may be placedcircumferentially about each of the segments and preferably runthroughout the length of the guide tube through each of the individualsegments. When the guide tube is to be rigidized, the tensioningelements may be pulled or tightened to draw the segments together suchthat the entire guide tube becomes rigid. The tensioning elements maythen be loosened such that the individual segments may move relative toone another.

[0011] In use, e.g., in the colon, the physician or surgeon maytypically first advance the distal portion of the endoscope within thebody of the patient. When the first curve of the colon is approached,the user may appropriately steer the distal portion of the endoscope toassume a curve for traversing the path. At this point, the endoscope ispreferably held stationary relative to the patient while the guide, in arelaxed and flexible state, is advanced over the shaft of the endoscopeuntil the distal end of the guide tube is at, or a short distance past,the distal tip of the endoscope. Once the guide tube, or at least itsdistal portion, has assumed the curve formed by the controllable distalportion of the endoscope, the guide tube may then be rigidized,preferably along its length, to hold its assumed shape. Once this isdone, the endoscope may be further advanced within the rigidized guidetube to traverse the curved pathway without having to place any pressureagainst the walls of the colon. The steps for advancing the endoscopemay be repeated as necessary until the desired area within the body hasbeen reached.

[0012] At any point during the exploratory procedure, the guide tube maybe removed from the colon while leaving the endoscope behind. To removethe assembly from the colon, the guide tube may first be withdrawn andthe endoscope may be subsequently withdrawn. Alternatively, the abovesteps may be repeated in reverse order to withdraw both the guide tubeand the endoscope from the region.

[0013] The outer surface of the guide tube preferably has a tubularcovering which covers at least a majority of the tube to prevent theentry of debris and fluids within the lumen of the guide tube betweenthe individual segments. The covering also facilitates the advancementand withdrawal of the guide tube by preventing tissue from being pinchedbetween the segments. To prevent tissue from being pinched between theguide tube and endoscope during assembly movement, expandable bellows oran additional covering may optionally be placed over the distal openingof the guide tube. This additional covering may simply be an integralextension of the covering over the surface of the guide tube, or it maybe a separate covering attached to the distal end of the guide tube.This covering may also be attached to or near the distal end of theendoscope to maintain a seal between the endoscope shaft and the guidetube. The coverings and their variations may be attached by anyconventional method as practicable. If the covering over the distal endof the guide tube is utilized, as the distal portion of the endoscopeshaft is advanced distally through the guide tube, the coveringpreferably expands distally along with the endoscope or simply slidesdistally along with the endoscope. When the shaft is retracted withinthe guide lumen, the covering again preferably retracts proximally alongwith the proximal movement of the distal end of the endoscope or it maysimply be retracted manually along with the endoscope. The use of theadditional covering may also aid in maintaining the sterility of theinternal lumen of the guide tube.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 shows a variation of the guide tube assembly in which anendoscope is pushed through and supported by a guide tube.

[0015]FIG. 2 shows a cross-sectional view of the guide tube assembly ofFIG. 1.

[0016]FIG. 3 shows the guide tube variation of FIG. 1 with a portion ofthe tube partially removed for clarity.

[0017]FIG. 4 shows a variation on a steerable endoscope having aselectively steerable distal portion and an automatically controllableproximal portion which may be used with the rigidizable guide tube.

[0018]FIG. 5 shows a wire frame model of a section of the automaticallycontrollable endoscope traversing an arbitrary curve.

[0019]FIG. 6A shows a variation in which the distal end of the endoscoperemains unattached to the flexible covering.

[0020]FIG. 6B shows another variation in which the distal end of theendoscope is attached to the flexible covering.

[0021]FIG. 7 shows the distal end of the endoscope extending past thedistal end of the guide tube and the flexible covering extendingdistally along with the endoscope.

[0022]FIG. 8A shows another variation in which the covering isconfigured as an elastic tubular structure.

[0023]FIG. 8B shows another variation in which the covering isconfigured as an elastic diaphragm structure.

[0024]FIG. 9 shows the variations of FIGS. 8A and 8B in which theendoscope is extended distally.

[0025]FIG. 10 shows yet another variation in which a plastic covering isused to cover the endoscope and guide tube.

[0026]FIGS. 11A to 11E show a variation on advancing an endoscopethrough a colon using the guide tube as support.

[0027]FIG. 12 shows a variation in which the guide tube may be withdrawnfrom the colon while leaving the endoscope behind.

DETAILED DESCRIPTION OF THE INVENTION

[0028] As shown in FIG. 1, a representative illustration of a variationon guide tube assembly 10 is seen partially disassembled for clarity.Assembly 10 generally comprises an endoscope 12 which is insertablewithin guide tube 14 through guide lumen 16. Endoscope 12 may be anyconventional type endoscope having a handle 18 with shaft 20 extendingtherefrom. The distal end of shaft 20 preferably comprises acontrollable distal portion 22 which may be manipulated to facilitatethe steering of the device through the body. Endoscope shaft 20 may beslidingly disposed within guide lumen 16 such that controllable distalportion 22 is able to be passed entirely through guide tube 14 and outdistal opening 24 defined at the distal end of tube 14.

[0029] Alternatively, guide tube 14 may also be used with an endoscopehaving an automatically controlled proximal portion and a selectivelysteerable distal portion, as described in further detail below. Such acontrollable endoscope may have a distal portion which is manuallysteerable by the physician or surgeon to assume a shape to traverse anarbitrary curved path and a proximal portion which is automaticallycontrolled by, e.g., a computer, to transmit the assumed shape along theproximal portion as the endoscope is advanced or withdrawn. Moredetailed examples are described in copending U.S. patent applicationSer. No. 09/969,927, which has been incorporated above by reference inits entirety.

[0030] One example of such an endoscope is shown in FIG. 4, which showsone variation of steerable endoscope 80. Endoscope 80 has an elongatebody 82 with a manually or selectively steerable distal portion 84 andan automatically controlled proximal portion 86. The selectivelysteerable distal portion 84 can be selectively steered or bent up to afull 180° bend in any direction. A fiberoptic imaging bundle 92 and oneor more illumination fibers 94 may extend through body 82 from proximalend 90 to distal end 88. Alternatively, endoscope 80 may be configuredas a video endoscope with a miniaturized video camera, e.g., a CCDcamera, positioned at distal end 88 of endoscope body 82. The imagesfrom the video camera may be transmitted to a video monitor by atransmission cable or by wireless transmission where images may beviewed in real-time or recorded by a recording device onto analogrecording medium, e.g., magnetic tape, or digital recording medium,e.g., compact disc, digital tape, etc. Optionally, body 82 of endoscope80 may include one or two instrument channels 96, 98 that may also beused for insufflation or irrigation, air and water channels, vacuumchannels, etc. Body 82 of endoscope 80 is preferably highly flexible sothat it is able to bend around small diameter curves without buckling orkinking while maintaining the various channels intact. When configuredfor use as a colonoscope, body 82 of the endoscope 80 may rangetypically from 135 to 185 cm in length and approximately 12-13 mm indiameter. Endoscope 80 can be made in a variety of other sizes andconfigurations for other medical and industrial applications.

[0031] A proximal handle 100 is attached to proximal end 90 of elongatebody 82. Handle 100 may include ocular 104 connected to fiberopticimaging bundle 92 for direct viewing and/or for connection to a videocamera 106 or a recording device 108. Handle 100 may be connected to anillumination source 110 by illumination cable 116 that is connected toor continuous with illumination fibers 94. A first luer lock fitting 112and a second luer lock fitting 114 on the handle 100 may be connected toinstrument channels 96, 98.

[0032] Handle 100 may be connected to an electronic motion controller122 by way of controller cable 118. Steering control 102 may beconnected to electronic motion controller 122 by way of a second cable120. Steering control 102 may allow the user to selectively steer orbend selectively steerable distal portion 84 of body 82 in the desireddirection. Steering control 102 may be a joystick controller as shown,or other known steering control mechanism. Electronic motion controller122 may control the motion of automatically controlled proximal portion86 of body 82. The electronic motion controller 122 may be implementedusing a motion control program running on a microcomputer or using anapplication-specific motion controller. Alternatively, electronic motioncontroller 122 may be implemented using, a neural network controller.

[0033] An axial motion transducer 124 may be provided to measure theaxial motion of the endoscope body 82 as it is advanced and withdrawn.The axial motion transducer 124 can be made in many possibleconfigurations. By way of example, the axial motion transducer 124 inFIG. 4 is configured as a ring 126 that may entirely or partiallysurround body 82 of endoscope 80. The axial motion transducer 124 ispreferably attached to a fixed point of reference, such as the surgicaltable or the insertion point for endoscope 80 on the patient's body. Asbody 82 of endoscope 80 slides through axial motion transducer 124, itproduces a signal indicative of the axial position of endoscope body 82with respect to the fixed point of reference and sends a signal toelectronic motion controller 122 by telemetry or by a cable (not shown).Axial motion transducer 124 may use optical, electronic or mechanicalmethods to measure the axial position of endoscope body 82. Otherpossible configurations for the axial motion transducer 124 are furtherdescribed in copending U.S. patent application Ser. No. 09/969,927.

[0034]FIG. 5 shows a wire frame model of a section of body 82 ofendoscope 80 in a neutral or straight position. Most of the internalstructure of endoscope body 82 has been eliminated in this drawing forthe sake of clarity. Endoscope body 82 is divided up into segments orsections 1, 2, 3, . . . , etc. The geometry of each segment is definedby four length measurements along the a, b, c and d axes and each of theadjacent segments are preferably interconnected via joints which allowthe independent angular movement and/or rotation of each segmentrelative to one another. For example, the geometry of segment 1 isdefined by the four length measurements l_(1a), l_(1b), l_(1c), l_(1d),and the geometry of segment 2 is defined by the four length measurementsl_(2a), l_(2b), l_(2c), l_(2d), etc. Each adjacent segment 1, 2, 3, . .. , etc., are preferably individually controlled by linear actuators(not shown), e.g., electric, pneumatic, hydraulic, etc. motors. Thelinear actuators may utilize one of several different operatingprinciples. For example, to bend the endoscope body 82 in the directionof the a axis, the measurements l_(1a), l_(2a), l_(3a) . . . l_(10a) canbe shortened and the measurements l_(1b), l_(2b), l_(3b) . . . l_(10b)would be lengthened an equal amount. The amount by which thesemeasurements are changed determines the radius of the resultant curve.Alternatively, individual motors may be actuated to move adjacentsegments relative to one another to effect a resultant curvature, asdescribed in further detail in U.S. patent application Ser. No.09/969,927.

[0035] In the automatically controlled proximal portion 86, each segmentmay be automatically controlled by electronic motion controller 122,which uses a curve propagation method to control the shape of endoscopebody 82. Endoscope body 82 has been maneuvered through the curve incolon C with the benefit of selectively steerable distal portion 84 andnow automatically controlled proximal portion 86 resides in the curve.When endoscope body 82 is advanced distally by one unit, segment 1 movesinto the position marked 1′, segment 2 moves into the positionpreviously occupied by segment 1, segment 3 moves into the positionpreviously occupied by segment 2, etc. The axial motion transducer 124produces a signal indicative of the axial position of endoscope body 82with respect to a fixed point of reference and sends the signal to theelectronic motion controller 122, under control of the electronic motioncontroller 122, each time endoscope body 82 advances one unit, eachsegment in automatically controlled proximal portion 86 is signaled toassume the shape of the segment that previously occupied the space thatit is now in. Thus, the curve propagates proximally along the length ofautomatically controlled proximal portion 86 of endoscope body 82. Thecurve appears to be fixed in space, as endoscope body 82 advancesdistally.

[0036] Similarly, when the endoscope body 82 is withdrawn proximally,each time endoscope body 82 is moved proximally by one unit, eachsegment in automatically controlled proximal portion 86 is signaled toassume the shape of the segment that previously occupied the space thatit is now in. The curve propagates distally along the length of theautomatically controlled proximal portion 86 of endoscope body 82, andthe curve appears to be fixed in space, as endoscope body 82 withdrawsproximally. Whenever endoscope body 82 is advanced or withdrawn, axialmotion transducer 124 preferably detects the change in position andelectronic motion controller 122 propagates the selected curvesproximally or distally along automatically controlled proximal portion86 of endoscope body 82 to maintain the curves in a spatially fixedposition. This allows endoscope body 82 to move through tortuous curveswithout putting unnecessary force on the walls of colon C.

[0037] One example of using assembly 10, e.g., in the colon, thephysician or surgeon may typically first advance distal portion 22 ofendoscope 12 within the body of the patient. Upon reaching the firstpoint at which endoscope 12 requires steering to negotiate a curvedpathway, the user may appropriately steer distal portion 22 to assume acurve for traversing the pathway. At this point with endoscope 12 heldstationary relative to the patient, guide tube 14 may be advanced overshaft 20 until the distal end of guide tube 14 is at, a short distancebefore, or a short distance past, the distal tip of controllable distalportion 22. The short distance is considered to range anywhere from afew centimeters to several inches. While guide tube 14 is advanced overshaft 20, tube 14 is preferably in a non-rigid state and is flexibleenough to assume the curve formed by controllable distal portion 22.

[0038] Once tube 14, or at least its distal portion, has assumed thecurve formed by controllable distal portion 22, tube 14 is rigidizedpreferably along its length to hold its assumed shape. Once this isaccomplished, shaft 20 of endoscope 12 may be further advanced withinthe rigidized guide tube 14 to traverse the curved pathway withouthaving to place any pressure against the walls of the colon.

[0039] Alternatively, if automatically controllable endoscope 80 isutilized, it may generally be used in the same manner as conventionalendoscope 12. However, because endoscope body 82 is automaticallycontrollable either along its entire length or along several segmentsproximally of steerable distal portion 84, the steerable distal portion84 may be advanced farther past the distal end of guide tube 14 thanmight be possible with conventional endoscope 12. Controllable endoscope80 may be used in all other aspects similarly as conventional endoscope12 as described herein.

[0040] Returning to FIG. 1, bellows or covering 26 may cover distalopening 24 of guide tube 14 to prevent the entry of debris and fluidswithin guide lumen 16. As distal portion 22 of shaft 20 is advanceddistally through tube 14 and out of guide lumen 16, covering 26 ispreferably configured to expand distally either over or with shaft 20while maintaining a seal with guide lumen 16. When shaft 20 is retractedwithin guide lumen 16 or when guide tube 14 is advanced distallyrelative to shaft 20, covering 26 is preferably configured to retractproximally back over distal opening 24 along with the proximal movementof distal portion 22. The use of covering 26 is optional and may be usedto maintain the sterility of guide lumen 16. Covering 26 may also beused to prevent the pinching and tearing of tissue when shaft 20 iswithdrawn within guide lumen 16.

[0041] Guide tube 14 may be any conventional appropriately flexibleconduit which is capable of being rigidized along its entire length. Thevariation shown in FIG. 1 is comprised of a plurality of individualsegments 28 which are linked adjacent to one another via several, i.e.,more than one, tensioning wires or elements 30. Segments 28 may be aseries of interconnecting ball-and-socket type segments which allowadjacent segments 28 to angularly pivot relative to one another to forman angle for traversing curves. These segments 28 may be rigidized viatensioning elements 30 which may be placed circumferentially aboutsegments 28, as shown in FIG. 2, which is a cross-sectioned view ofassembly 10 from FIG. 1. In this variation, there are four tensioningwires 30A, 30B, 30C, 30D which are each placed 90° relative to oneanother. Although four wires are shown in this example, a fewer numberof wires may also be used, e.g., three wires. Each of these wires 30A,30B, 30C, 30D may be routed through an integral channel or lumen definedin the walls of each segment 28. Moreover, they may be individuallymanipulated or they may all be manipulated simultaneously to effect atensioning force for either rigidizing or relaxing guide tube 14 alongits length.

[0042]FIG. 2 also shows the relative positioning of shaft 20 in relationto segment 28. As seen, shaft 20, which may contain any number ofchannels 34 for illumination fibers, optical fibers, etc., and workingchannels 34, is slidingly disposed within guide lumen 16. This variationshows a gap separation between the outer surface of shaft 20 and theinner surface of segment 28. This gap may vary depending upon thediameter of the endoscope being used and the desired cross-sectionalarea of guide tube 14, but a nominal separation is preferable to allowthe uninhibited traversal of shaft 20 within guide lumen 16. An exampleof a rigidizable conduit structure which may be utilized as part of thepresent invention is shown and described in further detail in U.S. Pat.No. 5,251,611 to Zehel et al., which is incorporated herein by referencein its entirety.

[0043] The outer surface of guide tube 14 preferably has a tubularcovering 32 which covers at least a majority of tube 14. Tubularcovering 32 may provide a barrier between the debris and fluids of thebody environment and the interior guide lumen 16, if also used withcovering 26. Moreover, covering 26 may be an integral extension oftubular covering 32 and may accordingly be made from a continuous layerof material. Tubular covering 32 may also provide a lubricous cover tofacilitate the insertion and movement of guide tube 14 along the wallsof the body lumen as well as to provide a smooth surface inbetween theindividual segments 28 to prevent the tissue from being pinched ortrapped. Tubular covering 32 may be made from a variety of polymericmaterials, e.g., PTFE, FEP, Tecoflex, etc.

[0044]FIG. 3 shows a side view of guide tube variation 14 with a portionof the wall partially removed for clarity. As shown, individual segments28 are aligned adjacent to one another with interconnecting sleeves 40placed inbetween. Sleeves 40, in this variation, may be used to providea pivoting structure to allow guide tube 14 to flex into differentpositions. Alternatively, segments 28 may be curved ball-and-socket typejoints configured to interfit with one another. Tubular covering 32 mayalso be seen to cover at least the majority of guide tube 14.Optionally, a distal end portion of guide tube 14 may be configured tobe controllable such that guide tube 14, like the controllable distalportion 22 of the endoscope 12, may define an optimal path fortraversal.

[0045] Bellows or covering 26 may optionally be appended to the distalend of conventional endoscope shaft 20 or controllable shaft 82.Throughout the description herein, automatically controllable endoscope82 may be interchanged with conventional endoscope 12 when used in guidetube 14 as well as with the use of bellows or covering 26. Althoughdescriptions on the method of use may describe use with conventionalendoscope 12, this is done for brevity and is not intended to belimiting. The description is intended to apply equally to use withcontrollable endoscope 80 since the two may be easily interchangeddepending upon the desired use and result. FIG. 6A shows one variationin which shaft 20 or 80 is unattached to covering 26 such that endoscope12 may be freely inserted and withdrawn from guide lumen 16. Covering 26may be omitted altogether from the assembly but is preferably used notonly to help maintain an unobstructed guide lumen 16, but also toprevent the walls of the body lumen from being pinched between theendoscope shaft 20 or 80 and guide tube 14 during advancement of theassembly. As seen in FIG. 6A, covering 26 may be separately attached atattachment region 50 to the outer surface or distal edge of guide tube14. Covering 26 may also further comprise a gusseted region 52 whichallows the covering 26 to be compressed into a small compact profile andexpanded much like a bellows during shaft 20 or 80 advancement. Whenshaft 20 or 80 is withdrawn, gusseted region 52 may allow covering 26 torecompress or reconfigure itself back into its compacted shape. In thisvariation, covering 26 is unattached to shaft 20 or 80; therefore, oncethe assembly has reached a predetermined location within the colon,covering 26 may be removed through a working channel within endoscope 12or the working tools may simply be pierced through covering 26, althoughthis is less preferable, before a procedure may be begin.

[0046]FIG. 6B shows another variation where covering 26 may be attachedto the endoscope shaft 20 or 80 near or at the distal end ofcontrollable distal portion 22 along attachment region 54. As shaft 20or 80 is advanced or withdrawn from guide lumen 16, covering 26 remainsattached to the endoscope 12. FIG. 7 shows shaft 20 or 80 being advancedto a distal position through guide lumen 16. As shaft 20 or 80 isadvanced, gusseted region 52 may be seen expanding to accommodate thedistal movement. The gusseted region 52 may be configured to allow shaft20 or 80 to be advanced to any practical distance beyond guide tube 14,e.g., a few or several inches, depending upon the application. With thisvariation, shaft 20 or 80 may be extended through guide lumen 16 to thisdistal position prior to first advancing shaft 20 or 80 within the colonof a patient as well as to allow enough room so that the controllabledistal portion 22 may have enough space to be manipulated to assume adesired shape or curve over which guide tube 14 may be advanced over.

[0047] Another variation is shown in FIG. 8A in which covering 60 may beconfigured as an elastic tubular member. As seen, when endoscope shaft20 or 80 is in a retracted position, covering 60 may be configured toform a tubular structure when relaxed. As endoscope shaft 20 or 80 isadvanced distally, as seen in FIG. 9, covering 60 may stretch along withshaft 20 or 80 to maintain the sterility of guide lumen 16.

[0048] Yet another variation is shown in FIG. 8B in which covering 62may be configured as an elastic rolling diaphragm. When endoscope shaft20 or 80 is retracted, covering 62 may be configured to evert uponitself such that part of covering 62 may be pulled proximally into guidelumen 16. Such a covering 62 material may comprise any number ofelastomers, elastomeric materials, or rubber-type materials, e.g.,neoprene or latex. When endoscope shaft 20 or 80 is advanced distally,covering 62 may likewise revert and stretch distally along with shaft 20or 80, also as shown in FIG. 9.

[0049] Alternatively, the covering may simply be a plastic covering orwrapper 64 which is non-elastic, as shown in FIG. 10. Such coverings 64are conventionally available and may be advanced along with endoscopeshaft 20 or 80 and retracted likewise as endoscope shaft 20 or 80 isretracted.

[0050]FIGS. 11A to 11E show one variation of advancing a conventionalendoscope 12 using the guide tube 14. FIG. 11A shows an illustrativecolon C of a patient. Endoscope 12 may be inserted within colon Cthrough the anus A of the patient. As the distal portion 22 is advancedthrough rectum R, it encounters its first point of curvature. Here,controllable distal portion 22 may be manipulated much as a conventionalendoscope to select an optimal path into sigmoid colon S. The optimalpath is one which presents the most efficient path for advancingendoscope 12 with the least amount of contact against the walls of colonC.

[0051] Once distal portion 22 has been manipulated to select theappropriate shape, guide tube 14 may be advanced through anus A andrectum R over endoscope 12 while endoscope 12 is maintained stationaryrelative to colon C. Guide tube 14 is preferably in a relaxed state andis able to conform easily to the shape defined by controllable distalportion 22. Guide tube 14 may be advanced to the distal end of distalportion 22, a short distance before, or a short distance past the distalend of portion 22, as shown in FIG. 11B. Once guide tube 14 has beenadvanced distally, it may be rigidized along its length such that itmaintains the shape defined by endoscope 12.

[0052] Then, with guide tube 14 rigidized, it is preferably heldstationary relative to colon C while endoscope 12 is further advancedthrough guide tube 14 until distal portion 22 reaches the next point ofcurvature. Controllable distal portion 22 may then be manipulated toselect an optimal path into descending colon D, as shown in FIG. 11C.Once the optimal path has been selected, endoscope 12 is preferablymaintained stationary relative to colon C while guide tube 14 is placedinto its relaxed state and advanced over endoscope 12. Guide tube 14 maybe advanced distally until the distal end of endoscope 12 is reached, asshown in FIG. 11D. At this point, guide tube 14, having assumed theshape defined by controllable distal portion 22, may be rigidized alongits length to maintain this shape. Endoscope 12 may then be advanceddistally again, as seen in FIG. 11E, while using the rigidized guidetube 14 to provide the column strength to advance endoscope 12 withoutthe need to unnecessarily contact the walls of colon C. Endoscope 12 maybe advanced until distal portion 22 reaches the flexure betweendescending colon D and transverse colon T. Once this point is reached,the steps described above may be repeated as necessary until endoscope12 has negotiated its way through transverse colon T, and ascendingcolon G until cecum E has been reached, or until a desired locationwithin colon C has been reached.

[0053] At any point during the exploratory procedure, guide tube 14 maybe removed from colon C while leaving endoscope 12 behind, as shown inFIG. 12 by tube withdrawal 70. If endoscope 12 were left within colon C,the endoscope 12 may be used and manipulated as any conventionalendoscope or colonoscope would be during a conventional colonoscopyexamination. Guide tube 14 may also be partially retracted to allow thedistal portion 22 to be steered or manipulated to examine or treat thecolon C while still providing support and guidance to the proximal scopesection of endoscope 12. To remove the assembly from colon C, guide tube14 may first be withdrawn, as shown, and endoscope 12 may besubsequently withdrawn. Alternatively, the above steps may be repeatedin reverse order to withdraw both guide tube 14 and endoscope 12 fromcolon C.

[0054] The applications of the guide tube system and methods of usediscussed above are not limited to regions of the body but may includeany number of further treatment applications. Other treatment sites mayinclude areas or regions of the body around organ bodies. Additionally,the present invention may be used in other environments which presenttortuous paths such as exploratory procedures on piping systems, ducts,etc. Moreover, various other rigidizable guide tube apparatus andapplications may be utilized beyond what is described herein.Modification of the above-described assemblies and methods for carryingout the invention, and variations of aspects of the invention that areobvious to those of skill in the art are intended to be within the scopeof the claims.

What is claimed is:
 1. An apparatus for advancing a diagnostic ortherapeutic instrument into a hollow body organ, comprising: a guidetube having an elongated portion, a distal opening and a lumen extendingtherethrough to permit passage of a diagnostic or therapeuticinstrument; a flexible covering encapsulating at least a portion of theguide tube; and an atraumatic distal region adjacent to the distalopening adapted to be atraumatic in the vicinity of the distal openingsuch that tissue is prevented from pinching or tearing when thediagnostic or therapeutic instrument is translated through the distalopening.
 2. The apparatus of claim 1 wherein the guide tube includes amechanism for locking the guide tube in a bent configuration.
 3. Theapparatus of claim 2 wherein the mechanism for locking the guide tube ina bent configuration comprises: a plurality of nestable elements; aplurality of tension wires that thread the nested elements together; anda tensioning mechanism that may be releasably coupled to the pluralityof tension wires and to selectively apply a clamping load to theplurality of nestable elements.
 4. The apparatus of claim 2 wherein themechanism for locking the guide tube in a bent configuration comprises:a plurality of links, each link having a bore that defines the lumen ofthe guide tube; and a device for applying a clamping load to theplurality of links.
 5. The apparatus of claim 1 wherein the flexiblecovering is integrated with the guide tube.
 6. The apparatus of claim 1wherein the flexible covering is integral with the atraumatic distalregion.
 7. The apparatus of claim 1 wherein the atraumatic distal regioncomprises an elastic tubular member.
 8. The apparatus of claim 1 whereinthe atraumatic distal region comprises an elastic diaphragm.
 9. Theapparatus of claim 1 wherein the first diagnostic or therapeuticinstrument has a steerable distal tip, and the distal region of theguide tube comprises a flexible material deflectable by the steerabledistal tip of the first diagnostic or therapeutic instrument.
 10. Theapparatus of claim 1 wherein the lumen is dimensioned to permit passageof a second diagnostic or therapeutic instrument alongside thediagnostic or therapeutic instrument.
 11. A method for advancing adiagnostic or therapeutic instrument having a steerable distal end intoa hollow body organ, comprising: providing a guide tube having anelongated portion with a distal opening and a lumen extendingtherethrough to permit passage of the diagnostic or therapeuticinstrument, and an atraumatic distal end disposed adjacent the distalopening; inserting the guide with the diagnostic or therapeuticinstrument into the hollow body organ; and preventing tissue of thehollow body organ from pinching or tearing via a flexible coveringencapsulating at least a portion of the guide tube when the diagnosticor therapeutic instrument is translated through the distal opening. 12.The method of claim 11 wherein providing the guide tube comprisesproviding the guide tube having a plurality of nestable elements, and atensioning mechanism that selectively applies a clamping load to theplurality of nestable elements.
 13. The method of claim 12 furthercomprising locking the guide tube in a bent configuration by actuatingthe tensioning mechanism.
 14. The method of claim 11 wherein providingthe guide tube comprises providing the guide tube having a plurality oflinks, each link having a bore that defines the lumen of the guide tube.15. The method of claim 14 further comprising locking the guide tube ina bent configuration by applying a clamping load to the plurality oflinks.
 16. The method of claim 11 wherein providing the guide tubefurther comprises inserting the diagnostic or therapeutic instrumentthrough the lumen such that the steerable distal tip is aligned with thedistal opening.
 17. The method of claim 16 further comprising navigatingthe diagnostic or therapeutic instrument with the guide tube through thehollow body organ by steering the steerable distal end of the diagnosticor therapeutic instrument.
 18. The method of claim 11 further comprisinglocking the guide tube in a bent configuration.
 19. The method of claim18 further comprising advancing the diagnostic or therapeutic instrumentthrough the lumen of the guide tube in the bent configuration.
 20. Themethod of claim 11 wherein providing the guide tube comprises advancinga second diagnostic or therapeutic instrument within the guide tubealongside the diagnostic or therapeutic instrument.